With charge-coupled device (CCD)-type and amplifier-type solid-state imaging devices for digital still cameras and camcorders, miniaturization of pixels has been demanded to obtain high definition images. However, reducing the size of a pixel decreases the light-receiving area of a photoelectric conversion element for light detection included in the pixel, resulting in degraded sensitivity.
Patent Document 1 discloses an amplifier-type complementary metal-oxide semiconductor (CMOS) solid-state imaging device fabricated by bonding a first substrate provided with photoelectric conversion elements and transfer transistors, and a second substrate provided with other circuits to ensure the light-receiving area of a photoelectric conversion element. The first and second substrates are bonded with each other by using copper bonding pads.
Further, with the solid-state imaging device discussed in Patent Document 1, connecting portions penetrating the second substrate are connected with input/output pads for connection with external terminals from the back face of the second substrate. The input/output pads are formed after the second substrate has been ground to expose connecting portions.